Diphenylamine, condensation with acids

Heating the sugar with strong acid yields furfural derivatives. Aldohexoses can eliminate water and formaldehyde under these conditions yielding furfural. This adehyde reacts with amines according to I to yield colored Schiff s bases. Ketohex-oses condense with diphenylamine in acid medium with simultaneous oxidation according to II to yield the condensation product shown. 

Diphenylamine—Phosphoric Acid Reagent), these condense with aniline to Schiff s... 

In the presence of anions which are precipitated by calcium chloride solution, proceed as follows. Precipitate the acetic acid test solution with calcium chloride solution, and collect the precipitate on a filter or in a centrifuge tube. Remove the water from the precipitate either by drying or by washing with alcohol and ether. Mix a small amount of the precipitate with diphenylamine in a dry micro test-tube, add a little concentrated phosphoric acid, and heat gently over a free flame. Calcium phosphate and free oxalic acid are formed, and the latter condenses with the diphenylamine to aniline blue and colours the hot phosphoric acid blue. The colour disappears on cooling. Dissolve the melt in alcohol, when a blue colouration appears. Pour the alcoholic solution into water thus precipitating the excess of diphenylamine, which is coloured light blue by the adsorption of the dyestuff. The dye may be extracted from aqueous solution by ether. 

Aromatic amine antioxidants were prepared by condensation of aniline, aralkylated diphenylamine or 2,2,4-trimethyl-l,2-dihydroquinoline with formaldehyde [165]. The latter was also used for the synthesis of other stabilizers a LS was formed via condensation with 2,4-dihydroxybenzophenone [166], a MD 131 with 2-hydroxy 4-methoxyacetophenone [167], another MD was formed with 8-hydroxyquinoline [168] and a BIO-S 132 with 4-aminosalicylic acid [169]. 

Diphenylamine-o-arsinic acid (V), prepared by the condensation of o-bromophenylarsinic acid and aniline, when reduced in alcoholic hydrochloric acid by sulphur dioxide in the presence of iodine, gives lO-chloro-5 10-dihydrophenarsazine, or if boiled with concentrated hydrochloric acid yields the chloride of phenarsazinic acid, which may be reduced to the 10-chloro-compound under suitable conditions. 2-Methyl- and 4-methyldiphenylamine-6 -arsinic acids are also capable of undergoing similar reactions to those just indicated. 

Nucleic acids can also be quantified by derivat-ization. Thus, RNA is subjected to a multistep procedure in which the nucleic acids are decomposed to pentoses, which are subsequently converted into furfural by heating in an acidic medium. The furfural in turn reacts with orcinol to form a bluish-green condensation product with /lmax = 660nm. The de-oxyribose of DNA is quantified with diphenylamine in an acid medium. The linear determination range is from 10 to 100 tgml and the procedure is free from the interference of RNA. 

There are a number of well-known colour tests for monosaccharides, such as condensation of the acid degradation products with phenolic substances. Perhaps the most frequently cited example of this is the Molisch test in which carbohydrates give a purple colour with a-naphthol in the presence of concentrated sulphuric acid. The presence of ketoses and of 3,6-anhydro-hexoses is often detected by the characteristic red colour rapidly developed with acid resorcinol (Seliwanoff test), and the presence of 2-deoxypentoses may be shown by the deep blue colour they yield with diphenylamine after degradation with acid to 5-hydroxy-levulinaldehyde. Before an individual sugar can be identified, however, it must be isolated as a pure substance in crystalline form or converted to a characteristic crystalline derivative. The derivative the author considers the best for the characterisation of the better known monosaccharides is given in Table I (p. 57). 

Qualitative Analysis. Several quaUtative analyses can be employed. For example, in the oxamide method (59), oxaUc acid is first heated at approximately 200°C with concentrated aqueous ammonia in a sealed tube. When thiobarbituric acid is added and heated to 140°C, a condensed compound of red color forms. The analysis limit is 1.6 pg. In the diphenylamine blue method (59,60), oxaUc acid is heated with diphenylamine to form a blue color, aniline blue. The analysis limit is 5 pg. 

An acridine with a radically different substitution pattern, interestingly, still exhibits antimalarial activity. Condensation of acetone with diphenylamine in the presence of strong acid affords the partly reduced acridine, 20. Alkylation with 3-chloro-dimethylaminopropane (via the sodium salt of 20) affords dimethacrine (21). ... 

Dinitro-diphenylamin)-<3 azo-3> (2 .4 -dinitro-diphenylamin) in Ger], [(02N)2CgH3-NH.CgH4.N. ]2 mw 544.43, N 20.58% golden-yel ndls(from pyridine), mp 285° sol in hot pyridine and in benzoic acid ethylester insol in other solvs was prepd by the condensation of 3"amino -3 -(2,4-dinitroanilino)-azobenzene with 4-chloro -1,3-dinxtrobenzene... 

In the latter preparation, the dichloroarsine is obtained from 2-nibro-diphenylamme-Q -arsinic add. This is prepared by the condensation of o-aminophenylarsinic acid and o-bromonitrobenzene in amyl alcohol in the presence of copper powder and potassium carbonate. It crystallises in golden-yellow ne les, melting with decompositioir at 288° to 240° C. "When reduced in alcoholic concentrated hydrochloric acid solution by sulphur dioxide in the presence of iodine, it yields 2-nitro-diphenylamine-6 -dichloroarsine, which crystallises from benzene-light petroleum in deep red crystals, M.pt. 110° C. 

Arylation involves the reaction between amines and phenols, aryl halides and aryl amines, including aniline. In arylation, one reactant acts as solvent acidic catalysts and high temperatures are employed. Diphenylamine (A-phenylbenzeneamine, /V-phenylani-line) (8) is made by condensation of aniline in the presence of a small amount of mineral acid catalyst at around 300 °C catalytic reaction of chlorobenzene with aniline at high temperature and pressure and continuous vapor-phase catalytic condensation of aniline. It is a useful intermediate in azo dye manufacture. Crompton is the main US manufacturer of 8, producing 1.3 billion lbs. in 2000. Applications include as lube additives... 

Quinacrine may be easily prepared starting form 2,4-dichlorobenzoic acid (90). Ullmann reaction of 90 with p-anisidine (91) gives the desired diphenylamine 92, which is cyclised to form the 9-chloroacridine derivative (93). Condensation of the latter with l-diethylamino-4-aminopentane affords quinacrine (22) [71]. A similar sequence of reaction starting from 90 and 5-amino-2-methoxypyridine (94) gives azocrine (28) [72] (Scheme 3). 

A conventional synthesis of tecleanthine (50) has been executed. Ullmann reaction of 2-amino-3-methoxybenzoic acid with 3-methoxy-4,5-methylene-dioxyiodobenzene gave the diphenylamine (49). Compound (49) was converted by cyclization (POCI3), hydrolysis (HCl), and methylation into tecleanthine (50). The Ullmann condensation was also used to prepare the natural acridones (48 R = R = R = R = OMe) and xanthoxoline (48 R = OH, R = R = R = H, iV-demethyl). The corresponding 9-thioketones were also synthesized. 

Other recent relevant developments have been the replacement of conventional acid catalysts with greener analogues. Direct esterification of carbo Q lic acids and alcohols continues to be a focus of attention. As examples, diphenylammonium triflate 8 and bulky diatylammonium sulfonates were shown to catalyse ester condensation of carboxylic acids and alcohols efficiently, and without the need for azeotropic water removal in the former case. Pentafluorophenylammonium triflate 9 was shown to be an efficient and cost-effective catalyst not only for esterification, but also for thioesterification, transesterification and macrolactone formation without requiring a dehydrating system. The superior catal)4ic efficiency of 9 relative to 8 was ascribed to the lower basicity of the pentafluoroaniline counter amine compared to diphenylamine. In related work, polyaniline... 

Diphenylamine is produced by the condensation of aniline in the presence of small amounts of mineral acid, with the release of ammonia. The crude diphenyl-amine/aniline mixture is refined by fractional distillation. Diphenylamine can also be produced by the reaction of chlorobenzene and aniline under pressure CU2O/ KCl is used as a catalyst. 

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